1. Field of the Invention
The present invention relates generally to telecommunication systems and in particular, to a method and a device for transferring signals representative of a pilot symbol pattern to a telecommunication device.
2. Description of the Related Art
In some telecommunication networks, the access by the mobile terminals to the resources of the telecommunication medium is decided by the base station.
In uplink scheduling scheme, when a mobile terminal needs to transfer data through the base station, the mobile terminal sends a message to the base station requesting a pilot symbol pattern to be allocated. The base station allocates to each mobile terminal a pilot symbol pattern, for a pilot allocation time duration which is as example of 20 milliseconds. During the pilot allocation time duration, each second telecommunication device 20 transfers periodically, as example every millisecond and at the same time to the base station, signals representative of the pilot symbol pattern it has been allocated.
The base station determines the channel conditions which exist between itself and each mobile terminal using the signals received which are representative of the pilot symbol patterns. The base station selects the mobile terminal which has to transfer data to the base station according to the determined channel conditions.
In such technique, when a mobile terminal needs to transfer data to the base station, it must transfer periodically as example every millisecond, during all the pilot allocation time duration, signals representative of the pilot symbol pattern to the base station.
If the channel conditions which exist between that mobile terminal and the base station are better than the ones which exist between the other mobile terminals and the base station, the base station selects that mobile terminal as the one which has to transfer data to the base station. However, the selected terminal may have no more data to transfer to the base station. In such case, the resources of the telecommunication system are used inefficiently.
Furthermore, if the mobile terminal has no more data to transfer, it must use the electric power resources in order to transfer periodically signals representative of the pilot symbol pattern to the base station. Such case is not satisfactory also in term of electric power consumption.
One solution could be to reduce the pilot allocation time duration in order to avoid that problem but such solution increases a lot the messages exchanged between the mobile terminals and the base station and then, the resources of the telecommunication system are still used inefficiently.
The patent U.S. Pat. No. 6,285,663 discloses a method wherein pilot signals are modulated by power control information.
It has to be noted also that, in the prior art, the pilot symbol patterns are transferred for the only purpose of the channel conditions determination.